Realizing Antithermal Quenching Red Emission in Mn-Activated RbNaVF for Optical Thermometry Sensor Application.

Currently, the development of red Mn-activated fluoride luminescent materials attracts a lot of attention in optical thermometry sensors, solid lighting, display, and plant growth areas. Nevertheless, the thermal stability of Mn-activated fluoride luminescent materials is still a crucial issue. Herein, a new red RbNaVF:Mn luminescent material with outstanding thermal stability was successfully synthesized through the facial coprecipitation method. Mn ions prefer to occupy VF octahedra based on the accurate Rietveld refinement results. Accordingly, the as-prepared RbNaVF:Mn exhibits a broad absorption region from 300 to 500 nm with a maximum of 468 nm, matching well with the near-ultraviolet and blue InGaN chip. Upon 468 nm excitation, RbNaVF:Mn can emit narrow-band red light at 632 nm. Notably, RbNaVF:Mn shows superior antithermal quenching properties, of which the integrated intensities at 175°C can realize as high as 140% than that at 25°C. Owing to the diverse thermal quenching behavior between anti-Stokes and Stokes emission, RbNaVF:Mn displays promising candidates in optical thermometry sensors with a relative sensitivity S of 0.49%. This study offers new insight into developing antithermal quenching red Mn-activated fluoride luminescent materials.